Chapter 9: Cardiac Muscle; The Heart as a Pump and Function of the Heart Valves Flashcards
The Heart; Two separate pumps
• Right Heart- pumps blood through the lungs
• Left Heart- pumps blood through the Peripheral organs
Each of the heart is a pulsatile two-chamber pump composed of an?
atrium and ventricle
Each atrium is a ____________ for the ventricle, helping to move blood into the ventricle
weak primer pump
The ventricles then supply the main pumping force that propels the blood either;
- through the pulmonary circulation by the right ventricle
- through the peripheral circulation by the left ventricle
special mechanisms in the heart cause a continuing succession of heart contractions called?
cardiac rhythmicity
transmitting action potentials throughout the cardiac muscle to cause the heart’s rhythmical beat
cardiac rhythmicity
The Heart is composed of three major types of cardiac muscle;
✓ atrial muscle
✓ ventricular muscle
✓ excitatory and conductive muscle fibers
types of muscle contract in much the same way as skeletal muscle, except the duration of contraction is much longer
atrial and ventricular muscle
contract only feebly because they contain few contractile fibrils
specialized EXCITATORY and CONDUCTIVE fibers
they exhibit either automatic rhythmical electrical discharge in the form of action potentials or conduction of the action potentials through the heart, providing an excitatory system that controls the rhythmic beating of the heart
excitatory and conductive fibers
cardiac muscle is ___________ in the same manner as in skeletal muscle
striated
cardiac muscle has typical myofibrils that contain _________ and ___________ almost identical to those found in skeletal muscle
actin and myosin filaments
these filaments lie side by side and slide along one another during contraction in the same manner as occurs in skeletal muscle
actin and myosin filaments
the dark areas crossing the cardiac muscle fibers
intercalated discs
cell membranes that separate individual cardiac muscle cells from one another
intercalated discs
are made up of many individual cells connected in series and in parallel with one another
cardiac muscle fibers
At each intercalated disc the cell membranes fuse with one another in such a way that they form permeable _____________ that allow rapid diffusion of ions
“communicating” junctions (gap junctions)
cardiac muscle is a ____________ of many heart muscle cells in which the cardiac muscles are so interconnected that when one of these cells become excited
syncytium
The heart actually is composed of two syncytiums;
✓ atrial syncytium
✓ ventricular syncytium
which constitutes the walls of the two atria
atrial syncytium
which constitutes the walls of the two ventricles
ventricular syncytium
The atria are separated from the ventricles by fibrous tissue that surrounds the _____________ openings between the atria and ventricles
ventricular (A-V) valvular
specialized conductive system
A-V bundle
a bundle of conductive fibers several millimeters in diameter
A-V bundle
Action potential of skeletal muscle is caused almost entirely by sudden opening of large numbers of so called?
fast sodium channels
allow tremendous numbers of sodium ions to enter the skeletal muscle fiber from the extracellular fluid
fast sodium channels
in cardiac muscle, the action potential is caused by opening two types of channels;
✓ fast sodium channels
✓ slow calcium channels
slow calcium channels which are also called?
calcium-sodium channels
a large quantity of both calcium and sodium ions flows through these channels to the interior of the cardiac muscle fiber, and this maintains a prolonged period of depolarization that cause __________ in the action potential
causing the plateau
